#ifndef _LINUX_USER_NAMESPACE_H
  #define _LINUX_USER_NAMESPACE_H
  
  #include <linux/kref.h>
  #include <linux/nsproxy.h>

  #include <linux/ns_common.h>

  #include <linux/sched.h>

  #include <linux/err.h>

  #define UID_GID_MAP_MAX_EXTENTS 5
  
  struct uid_gid_map {	/* 64 bytes -- 1 cache line */
  	u32 nr_extents;
  	struct uid_gid_extent {
  		u32 first;
  		u32 lower_first;
  		u32 count;
  	} extent[UID_GID_MAP_MAX_EXTENTS];
  };

  #define USERNS_SETGROUPS_ALLOWED 1UL
  
  #define USERNS_INIT_FLAGS USERNS_SETGROUPS_ALLOWED

  struct ucounts;

  
  enum ucount_type {
  	UCOUNT_USER_NAMESPACES,

  	UCOUNT_PID_NAMESPACES,

  	UCOUNT_UTS_NAMESPACES,

  	UCOUNT_IPC_NAMESPACES,

  	UCOUNT_NET_NAMESPACES,

  	UCOUNT_MNT_NAMESPACES,

  	UCOUNT_CGROUP_NAMESPACES,

  	UCOUNT_COUNTS,
  };

  struct user_namespace {

  	struct uid_gid_map	uid_map;
  	struct uid_gid_map	gid_map;

  	struct uid_gid_map	projid_map;

  	atomic_t		count;

  	struct user_namespace	*parent;

  	int			level;

  	kuid_t			owner;
  	kgid_t			group;

  	struct ns_common	ns;

  	unsigned long		flags;

  
  	/* Register of per-UID persistent keyrings for this namespace */
  #ifdef CONFIG_PERSISTENT_KEYRINGS
  	struct key		*persistent_keyring_register;
  	struct rw_semaphore	persistent_keyring_register_sem;
  #endif

  	struct work_struct	work;

  #ifdef CONFIG_SYSCTL
  	struct ctl_table_set	set;
  	struct ctl_table_header *sysctls;
  #endif

  	struct ucounts		*ucounts;

  	int ucount_max[UCOUNT_COUNTS];

  };
  
  struct ucounts {
  	struct hlist_node node;
  	struct user_namespace *ns;
  	kuid_t uid;
  	atomic_t count;

  	atomic_t ucount[UCOUNT_COUNTS];

  };
  
  extern struct user_namespace init_user_ns;

  
  bool setup_userns_sysctls(struct user_namespace *ns);
  void retire_userns_sysctls(struct user_namespace *ns);

  struct ucounts *inc_ucount(struct user_namespace *ns, kuid_t uid, enum ucount_type type);
  void dec_ucount(struct ucounts *ucounts, enum ucount_type type);

  
  #ifdef CONFIG_USER_NS
  
  static inline struct user_namespace *get_user_ns(struct user_namespace *ns)
  {
  	if (ns)

  		atomic_inc(&ns->count);

  	return ns;
  }

  extern int create_user_ns(struct cred *new);

  extern int unshare_userns(unsigned long unshare_flags, struct cred **new_cred);

  extern void __put_user_ns(struct user_namespace *ns);

  
  static inline void put_user_ns(struct user_namespace *ns)
  {

  	if (ns && atomic_dec_and_test(&ns->count))

  		__put_user_ns(ns);

  }

  struct seq_operations;

  extern const struct seq_operations proc_uid_seq_operations;
  extern const struct seq_operations proc_gid_seq_operations;
  extern const struct seq_operations proc_projid_seq_operations;

  extern ssize_t proc_uid_map_write(struct file *, const char __user *, size_t, loff_t *);
  extern ssize_t proc_gid_map_write(struct file *, const char __user *, size_t, loff_t *);

  extern ssize_t proc_projid_map_write(struct file *, const char __user *, size_t, loff_t *);

  extern ssize_t proc_setgroups_write(struct file *, const char __user *, size_t, loff_t *);
  extern int proc_setgroups_show(struct seq_file *m, void *v);

  extern bool userns_may_setgroups(const struct user_namespace *ns);

  extern bool current_in_userns(const struct user_namespace *target_ns);

  
  struct ns_common *ns_get_owner(struct ns_common *ns);

  #else
  
  static inline struct user_namespace *get_user_ns(struct user_namespace *ns)
  {
  	return &init_user_ns;
  }

  static inline int create_user_ns(struct cred *new)

  {

  	return -EINVAL;

  }

  static inline int unshare_userns(unsigned long unshare_flags,
  				 struct cred **new_cred)
  {
  	if (unshare_flags & CLONE_NEWUSER)
  		return -EINVAL;
  	return 0;
  }

  static inline void put_user_ns(struct user_namespace *ns)
  {
  }

  static inline bool userns_may_setgroups(const struct user_namespace *ns)
  {
  	return true;
  }

  
  static inline bool current_in_userns(const struct user_namespace *target_ns)
  {
  	return true;
  }

  
  static inline struct ns_common *ns_get_owner(struct ns_common *ns)
  {
  	return ERR_PTR(-EPERM);
  }

  #endif

  #endif /* _LINUX_USER_H */